Composition, cured product, storage container, image forming apparatus, and image forming method

ABSTRACT

Provided is a composition including an acrylamide compound (A1) having a molecular weight of 150 or greater but 250 or less, and a trifunctional or higher polymerizable compound (A2), wherein an amount of the trifunctional or higher polymerizable compound (A2) is 1% by mass or greater but 30% by mass or less relative to a total amount of the composition.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. §119 to Japanese Patent Application No. 2018-142147 filed Jul. 30, 2018 and Japanese Patent Application No. 2019-001011 filed Jan. 8, 2019. The contents of which are incorporated herein by reference in their entirety.

BACKGROUND OF THE INVENTION Field of the Invention

The present disclosure relates to a composition, a cured product, a storage container, an image forming apparatus, and an image forming method.

Description of the Related Art

As active energy ray-curable inks used for an inkjet printing system, radical polymerizable inks or cationic polymerizable inks have been used. Among such inks, radical polymerizable inks have been widely used in view of a production cost of inks and storage stability of inks.

As such a radical polymerizable ink, known in an ink including a polymerizable monomer, such as acrylic acid ester, and a polymerization initiator that generates radicals when active energy rays are applied.

For an active energy ray-curable composition, desired is an active energy ray-curable composition capable of producing a cured product having high hardness in view of productivity, improvement of curability, and handling of a cured product. After ejecting the active energy ray-curable composition onto a base and curing the active energy ray-curable composition, forming process is often performed as a post treatment.

In order to improve forming processability, curability, and hardness, therefore, for example, an active energy ray-curable composition in which an active energy ray-curable polyfunctional monomer is included has been proposed (see, for example, Japanese Patent No. 5606817, Japanese Patent No. 2938808, and Japanese Unexamined Patent Application Publication No. 2014-205839).

SUMMARY OF THE INVENTION

According to one aspect of the present disclosure, a composition includes an acrylamide compound (A1) having a molecular weight of 150 or greater but 250 or less, and a trifunctional or higher polymerizable compound (A2), wherein an amount of the trifunctional or higher polymerizable compound (A2) is 1% by mass or greater but 30% by mass or less relative to a total amount of the composition.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view illustrating an example of an image forming apparatus including an inkjet ejection unit;

FIG. 2 is a schematic view illustrating an example of another image forming apparatus (apparatus for forming 3D object); and

FIG. 3 is a schematic view for illustrating an example of a method for performing solid modeling using a composition.

DESCRIPTION OF THE EMBODIMENTS (Composition)

A composition of the present disclosure includes an acrylamide compound (A1) having a molecular weight of 150 or greater but 250 or less, and

a trifunctional or higher polymerizable compound (A2), wherein an amount of the trifunctional or higher polymerizable compound (A2) is 1% by mass or greater but 30% by mass or less relative to a total amount of the composition. The composition may further include other components according to the necessity.

The present disclosure has an object to provide a composition that has low viscosity and high curability, and is capable of forming a cured product of high hardness.

The present disclosure provides a composition that has low viscosity and high curability, and is capable of forming a cured product of high hardness.

The composition of the present disclosure has accomplished based on the following insights. In the related art, there are a problem that a composition including a large amount of a polyfunctional monomer has high viscosity and has poor ejection stability, hence it is difficult to obtain high hardness, and a problem that curing shrinkage of an obtained cured product (coated film or laminate thereof) occurs as an internal stress increases.

When a cured film is produced by a LED using the acrylamide compound having a molecular weight of 150 or greater but 250 or less (A1), both curability and hardness cannot be obtained at the same time. In order to solve the above-described problem that viscosity of a composition becomes high when only one polyfunctional monomer is used, the composition of the present disclosure has low viscosity, high curability, and can produce a cured product of high hardness because the composition includes an acrylamide compound (A1) of a molecular weight of 150 or greater but 250 or less, and a trifunctional or higher polymerizable compound (A2), where an amount of the trifunctional or higher polymerizable compound (A2) is 1% by mass or greater but 30% by mass or less relative to a total amount of the composition.

The composition of the present disclosure is preferably a curable composition. Examples of the curable composition include a heat-curable composition and an active energy ray-curable composition. Among the above-listed examples, an active energy ray-curable composition is more preferable.

<Acrylamide Compound (A1)>

The acrylamide compound (A1) includes an acrylamide group and has a molecular weight of 150 or greater but 250 or less. The acrylamide compound (A1) preferably further has an ester structure.

The molecular weight of the acrylamide compound (A1) is 150 or greater but 250 or less, and preferably 150 or greater but 200 or less. The molecular weight thereof being 150 or greater is preferable because odor generated by evaporation of the compound can be suppressed, and stability of inkjet ejection can be improved. The molecular weight thereof being 250 or less is preferable because curability of the composition becomes excellent, strength of a cured product improves, and moreover, viscosity of the composition is prevented from being too high.

In the present specification, (meth)acrylic acid ester means acrylic acid ester or methacrylic acid ester. (Meth)acrylate means acrylate or methacrylate.

The acrylamide compound (A1) is preferably a compound represented by General Formula (1), or General Formula (2), or both, more preferably a compound represented by General Formula (1) or General Formula (2), and even more preferably a compound represented by General Formula (1).

CH=CH—CO—N(R¹)—R²—CO—O—R³   General Formula (1)

In General Formula (1), R¹ is a hydrogen atom or a straight chain or branched alkyl group having from 1 through 4 carbon atoms, and is preferably a straight chain or branched alkyl group having from 1 through 4 carbon atoms. Examples of R¹ include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a sec-butyl group, an isobutyl group, and a tert-butyl group.

In General Formula (1), R² is a straight chain or branched alkylene group having from 1 through 4 carbon atoms. Examples of R² include a methylene group, an ethane-1,1-diyl group, an ethane-1,2-diyl group, a propane-1,1-diyl group, a propane-1,2-diyl group, a propane-1,3-diyl group, a butane-1,1-diyl group, a butane-1,2-diyl group, a butane-1,3-diyl group, a butane- 1,4-diyl group, a 2-methylpropane-1,1-diyl group, a 2-methylpropane-1,2-diyl group, and a 2-methylpropane-1,3-diyl group.

In General Formula (1), R³ is a straight chain or branched alkyl group having from 1 through 4 carbon atoms. Examples of R³ include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a sec-butyl group, an isobutyl group, and a tert-butyl group.

Note that, the total number of carbon atoms of R¹, R², and R³ is from 2 through 6.

In General Formula (2), a ring X is a cyclic structure that includes a nitrogen atom and has from 2 through 5 carbon atoms. Examples of the ring X include aziridine, azetidine, pyrrolidine, and piperidine. Among the above-listed examples, pyrrolidine and piperidine are preferable.

In General Formula (2), R⁴ is a single bond or a straight chain or branched alkylene group having from 1 through 3 carbon atoms. Examples of R⁴ include a single bond, a methylene group, an ethane-1,1-diyl group, an ethane-1,2-diyl group, a propane-1,1-diyl group, a propane-1,2-diyl group, and a propane-1,3-diyl group.

In General Formula (2), R⁵ is a straight chain or branched alkyl group having from 1 through 3 carbon atoms. Examples of R⁵ include a methyl group, an ethyl group, a propyl group, and an isopropyl group.

Note that, the total amount of carbon atoms of the ring X, R⁴, and R⁵ is from 3 through 6.

As a compound represented by General Formula (1) or (2), for example, N-acryloyl-N-alkylamino acid alkyl ester (including N-acryloylproline alkyl ester), and N-acryloylpiperidine carboxylic acid alkyl ester are preferable. The alkyl group in this paragraph means a straight chain or branched alkyl group having from 1 through 4 carbon atoms, and is preferably an alkyl group having 1 or 2 carbon atoms (i.e., a methyl group or an ethyl group).

The N-acryloyl-N-alkylamino acid alkyl ester is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include N-acryloyl-N-methylglycine methyl ester, N-acryloyl-N-methylglycine ethyl ester, N-acryloyl-N-methylglycine propyl ester, N-acryloyl-N-methylglycine butyl ester, N-acryloyl-N-ethylglycine methyl ester, N-acryloyl-N-ethylglycine ethyl ester, N-acryloyl-N-ethylglycine propyl ester, N-acryloyl-N-propylglycine methyl ester, N-acryloyl-N-propylglycine ethyl ester, N-acryloyl-N-butylglycine methyl ester, N-acryloyl-N-methylalanine methyl ester, N-acryloyl-N-methylalanine ethyl ester, N-acryloyl-N-methylalanine propyl ester, N-acryloyl-N-ethylalanine methyl ester, N-acryloyl-N-ethylalanine ethyl ester, N-acryloyl-N-propylalanine methyl ester, N-acryloyl-N-methyl-β-alanine methyl ester, N-acryloyl-N-methyl-β-alanine ethyl ester, N-acryloyl-N-ethyl-β-alanine methyl ester, N-acryloyl-N-ethyl-β-alanine ethyl ester, N-acryloyl-N-methylvaline methyl ester, N-acryloylproline methyl ester, and N-acryloylproline ethyl ester. The above-listed examples may be used alone or in combination.

The N-acryloylpiperidine carboxylic acid alkyl ester is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include methyl N-acryloylpiperidine-2-carboxylate, methyl N-acryloylpiperidine-3-carboxylate, and methyl N-acryloylpiperidine-4-carboxylate. The above-listed examples may be used alone or in combination.

In order to apply for an inkjet printing system, the acrylamide compound (A1) is preferably a colorless transparent or pale yellow transparent liquid having low viscosity (100 mPa·s or less) at room temperature (25° C.). For safety of users, moreover, the acrylamide compound (A1) is preferably a compound that does not exhibit strong acidity or basicity, and is free from harmful formaldehyde as impurities.

An amount of the acrylamide compound (A1) is preferably 20% by mass or greater but 98% by mass or less, more preferably 40% by mass or greater but 97% by mass or less, and further more preferably 64.8% by mass or greater but 96.8% by mass or less relative to a total amount of the composition.

<Trifunctional or Higher Polymerizable Compound (A2)>

The trifunctional or higher polymerizable compound (A2) is not particularly limited and may be appropriately selected depending on the intended purpose. The trifunctional or higher polymerizable compound (A2) is preferably trifunctional or higher but hexafunctional or less, and more preferably trifunctional in view of suppressing an increase in viscosity.

Examples of the trifunctional or higher polymerizable compound (A2) include glycerin tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, trimethylolpropane tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, ethoxylated isocyanuric acid tri(meth)acrylate, ε-caprolactone-modified tris-(2-(meth)acryloxyethyl)isocyanurate, ethoxy-modified ethylene glycol tri(meth)acrylate, ditrimethylol propane tetra(meth)acrylate, ethoxylated pentaerythritol tetra(meth)acrylate, N,N′,N″-tri(meth)acryloyldiethylenetriamine, N,N′-{[(2-acrylamide-2-[(3-acrylamidepropoxy)methyl]propane-1,3-diyl)bis (oxy)]bis(propane-1,3-diyl)}acrylamide, and N,N′,N″,N′″-tetra(meth)acryloyltriethylenetetramine. The above-listed examples may be used alone or in combination. Among the above-listed examples, glycerin tri(meth)acrylate, pentaerythritol tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, and trimethylolpropane tri(meth)acrylate are preferable in view of prevention of an increase in viscosity.

An amount of the trifunctional or higher polymerizable compound (A2) is 1% by mass or greater but 30% by mass or less, preferably 5% by mass or greater but 20% by mass or less, and more preferably 7% by mass or greater but 15% by mass or less relative to a total amount of the composition.

When the amount of the trifunctional or higher polymerizable compound (A2) is 1% by mass or greater but 30% by mass or less, the composition that has low viscosity and high curability, and can produce a cured product having high hardness can be obtained.

<Other Polymeric Compounds than Acrylamide Compound (A1) and Trifunctional or Higher Polymerizable Compound (A2)>

The composition of the present disclosure may include other polymeric compounds than the acrylamide compound (A1) and the trifunctional or higher polymerizable compound (A2).

As the above-mentioned other polymeric compounds, polymeric monomers know in the art, such as (meth)acrylic acid esters, can be used. Examples thereof include methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, allyl (meth)acrylate, glycidyl (meth)acrylate, 2-(dimethylamino)ethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-butoxyethyl (meth)acrylate, ethylcarbitol (meth)acrylate, cyclohexyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, 2-(2-vinyloxyethoxy)ethyl (meth) acrylate, benzyl (meth)acrylate, 2-phenoxyethyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, isobornyl (meth)acrylate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, tetrapropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, ethoxylated neopentyl glycol di(meth)acrylate, propoxylated neopentyl glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, and 1,9-nonanediol di(meth)acrylate. The above-listed examples may be used alone or in combination.

Examples of other polymerizable compounds include: a urethane (meth)acrylate derivative obtained by reacting (meth)acrylic acid ester having a hydroxyl group with a compound having an isocyanate group; and an epoxy(meth)acrylate derivative obtained by reacting (meth)acrylic acid with a compound having an epoxy group.

Other than the derivatives of (meth)acrylic acid, moreover, N-vinyl compounds (e.g., N-vinylcaprolactam, N-vinylpyrrolidone, and N-vinylformamide), aromatic vinyl compounds (e.g., styrene, and α-methylstyrene), vinyl ethers (e.g., diethylene glycol divinyl ether, triethylene glycol dlivinyl ether, and cyclohexane dimethanol divinyl ether), and allyl compounds (e.g., allyl glycidyl ether, diallyl phthalate, and triallyl trimellitate.

Note that, the above-mentioned arylamide compound that does not include an ester structure is also used as the above-mentioned other polymerizable compounds.

An amount of the above-mentioned other polymerizable compounds excluding the acrylamide compound (A1) and the trifunctional or higher polymerizable compound (A2) is preferably 1% by mass or greater but 30% by mass or less, and more preferably 5% by mass or greater but 20% by mass or less, relative to a total amount of the composition.

<Polymerization Initiator (B)>

The composition of the present disclosure may include a polymerization initiator. Note that, the polymerization initiator may be simply referred to as an initiator. As the polymerization initiator, there are a heat polymerization initiator and a photopolymerization initiator.

The photopolymerization initiator is not particularly limited as long as the photopolymerization initiator is capable of generating active species, such as radicals and cations, and inducing polymerization of a polymerizable compound (e.g., a monomer and an oligomer). As the photopolymerization initiator, any of radical polymerization initiators, cation polymerization initiators, base generators, etc., can be used alone or in combination. Among the above-listed examples, a radical polymerization initiator is preferable.

Examples of the radical polymerization initiator include aromatic ketones, acylphosphine oxide compounds, aromatic onium salt compounds, organic peroxides, thio compounds (e.g., thioxanthone compounds and thiophenyl group-containing compounds), hexaarylvbiimidazole compounds, ketoxime ester compounds, borate compounds, actinium compounds, metallocene compounds, active ester compounds, compounds including a carbon-halogen bond, and alkylamine compounds.

The radical polymerization initiator is not particularly limited and may be appropriately selected depending on the intended purpose.

Examples thereof include polyethylene glycol 200-di(β-4(4-(2-dimethylamino-2-benzyl)butanonylphenyl)piperazine) (Omnipol 910, available from IGM), 1,3-di({α-[1-chloro-9-oxo-9H-thioxanthen-4-yl)oxy]acetylpoly[oxy(1-methyl ethylene)]}oxy)-2,2-bis({α-[1-chloro-9-oxo-9H-thioxanthen-4-yl)oxy]acetylpoly[oxy(1-methylethylene)]}oxymethyl)propane (Speedcure7010, available from Lambson), a mixture of 1,3-di({α-4-(dimethylamino)benzoylpoly[oxy(1-methylethylene)]}oxy)-2,2-bis({α-4-(dimethylamino)benzoylpoly[oxy(1-methylethylene)]}oxymethyl)propane and {α-4-(dimethylamino)benzoylpoly(oxyethylene)-poly[oxy(1-methylethylene)]-poly(oxyethylene)}4-(dimethylamino)benzoate (Speedcure7040, available from Lambson), polybutylene glycol bis(9-oxo-9H-thioxanthinyloxy)acetate (Omnipol TX, available from IGM), a polymeric thioxanthene compound (Genepol TX-2, available from Lahn AG), and an oligomer of 2-hydroxy-1-(4-isopropenylphenyl)-2-methylpropan-1-one (Esacure ONE, available from IGM). The above-listed examples may be used alone or in combination.

In order to obtain sufficient curing speed, an amount of the polymerization initiator is preferably 1% by mass or greater but 20% by mass or less, more preferably 3% by mass or greater but 15% by mass or less, and even more preferably 5% by mass or greater but 10% by mass or less relative to a total amount of the composition.

In addition to the polymerization initiator, a polymerization accelerator (sensitizer) may be used in combination. The polymerization accelerator is not particularly limited and may be appropriately selected depending on the intended purpose. Examples of the polymerization accelerator include amine compounds, such as trimethyl amine, methyl dimethanol amine, triethanol amine, p-diethylaminoacetophenone, ethyl p-dimethylaminobenzoate, 2-ethylhexyl-p-dimethylaminobenzoate, and N,N-dimethylbenzylamine-4,4′-bis(diethylamino)benzophenone.

An amount of the polymerization accelerator is not particularly limited and may be appropriately set depending on a polymerization initiator for use or an amount of the polymerization initiator.

<Coloring Material>

The composition of the present disclosure may contain a colorant. As the colorant, various pigments and dyes may be used that impart black, white, magenta, cyan, yellow, green, orange, and gloss colors such as gold and silver, depending on the intended purpose of the composition and requisite properties thereof.

A content of the colorant in the composition is not particularly limited, and may be appropriately determined considering, for example, a desired color density and dispersibility of the colorant in the composition. However, it is preferably from 0.1% by mass to 20% by mass relative to the total mass of the composition. Incidentally, the composition of the present disclosure does not necessarily contain a colorant but can be clear and colorless. In such a case, for example, such a clear and colorless composition is good for an overcoating layer to protect an image.

The pigments include inorganic pigments and organic pigments. These can be used alone or in combination.

Specific examples of the inorganic pigments include, but are not limited to, carbon blacks (C.I. Pigment Black 7) such as furnace black, lamp black, acetylene black, and channel black, iron oxides, and titanium oxides.

Specific examples of the organic pigments include, but are not limited to, azo pigments such as insoluble azo pigments, condensed azo pigments, azo lakes, and chelate azo pigments, polycyclic pigments such as phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, thioindigo pigments, isoindolinone pigments, and quinofuranone pigments, dye chelates (e.g., basic dye chelates, acid dye chelates), dye lakes (e.g., basic dye lakes, acid dye lakes), nitro pigments, nitroso pigments, aniline black, and daylight fluorescent pigments.

In addition, a dispersant is optionally added to enhance the dispersibility of pigment. The dispersant has no particular limit and can be, for example, polymer dispersants conventionally used to prepare pigment dispersion (material).

The dyes include, for example, acidic dyes, direct dyes, reactive dyes, basic dyes, and combinations thereof.

<Organic Solvent>

The composition of the present disclosure optionally contains an organic solvent although it is preferable to spare it. The curable composition free of an organic solvent, in particular volatile organic compound (VOC), is preferable because it enhances safety at where the composition is handled and makes it possible to prevent pollution of the environment. Incidentally, the organic solvent represents a conventional non-reactive organic solvent, for example, ether, ketone, xylene, ethyl acetate, cyclohexanone, and toluene, which is clearly distinguished from reactive monomers. Furthermore, “free of” an organic solvent means that no organic solvent is substantially contained. The content thereof is preferably less than 0.1 percent by mass.

<Other Components>

The composition of the present disclosure optionally contains other known components. The other known components are not particularly limited. Specific examples thereof include, but are not limited to, surfactants, polymerization inhibitors, leveling agents, defoaming agents, fluorescent brighteners, permeation enhancing agents, wetting agents (humectants), fixing agents, viscosity stabilizers, fungicides, preservatives, antioxidants, ultraviolet absorbents, chelate agents, pH adjusters, (regulators), and thickeners.

Note that, each component in the composition can be analyzed as follows. Low molecular weight components, such as a polymerizable monomer and a polymerization initiator, can be determined by gas chromatography mass spectrometry. A principle skeleton of a polymer component or an amount of chlorine atoms therein can be determined by infrared spectroscopy or elemental analysis by precipitating and separating the polymer component using a poor solvent, such as methanol.

<Preparation of Composition>

The composition of the present disclosure can be prepared by using the components described above. The preparation devices and conditions are not particularly limited. For example, the composition can be prepared by subjecting the acrylamide compound (A1) having a molecular weight of 150 or greater but 250 or less, the trifunctional or higher polymerizable compound (A2), a pigment, a dispersant, etc., to a dispersion treatment using a dispersing machine such as a ball mill, a kitty mill, a disk mill, a pin mill, and a DYNO-MILL to prepare a pigment liquid dispersion, and further mixing the pigment liquid dispersion with a polymerizable monomer, an initiator, a polymerization initiator, and a surfactant.

<Viscosity>

The viscosity of the curable composition of the present disclosure has no particular limit because it can be adjusted depending on the purpose and application devices. For example, if an ejecting device that ejects the composition from nozzles is employed, the viscosity thereof is preferably in the range of 3 mPa·s to 40 mPa·s, more preferably 5 mPa·s to 15 mPa·s, and particularly preferably 6 mPa·s to 12 mPa·s in the temperature range of 20 degrees C. to 65 degrees C., preferably at 25 degrees C. In addition, it is particularly preferable to satisfy this viscosity range by the composition free of the organic solvent described above.

Incidentally, the viscosity can be measured by a cone plate rotary viscometer (VISCOMETER TVE-22L, manufactured by TOKI SANGYO CO.,LTD.) using a cone rotor (1°34′×R24) at a number of rotation of 50 rpm with a setting of the temperature of hemathermal circulating water in the range of 20 degrees C. to 65 degrees C. VISCOMATE VM-150III can be used for the temperature adjustment of the circulating water.

<Curing Unit>

The curable ink in accordance with some embodiments of the present invention comprises a curable composition. Preferably, the curable composition is cured by application of heat or irradiation with an active energy ray, and the latter is more preferable.

Specific examples of the active energy ray for curing the curable composition include, but are not limited to, electron beams, α-rays, β-rays, γ-rays, and X-rays, in addition to ultraviolet rays. When a light source having a particularly high energy is used, polymerization reaction can be allowed to proceed without a polymerization initiator. In addition, in the case of irradiation with ultraviolet ray, mercury-free is preferred in terms of protection of environment. Therefore, replacement with GaN-based semiconductor ultraviolet light-emitting devices is preferred from industrial and environmental point of view. Furthermore, ultraviolet light-emitting diode (UV-LED) and ultraviolet laser diode (UV-LD) are preferable as an ultraviolet light source. Small sizes, long time working life, high efficiency, and high cost performance make such irradiation sources desirable.

Among the above-listed examples, ultraviolet rays having a peak in the wavelength range of 285 nm or longer but 405 nm or shorter (preferably 365 nm or longer but 405 nm or shorter) emitted from a UV ray emitting diode (may be also referred to as UV-LED hereinafter) are preferable in view of energy saving and downsizing of a device. Note that, a light absorption spectrum of the polymerization initiator is typically broad. Use of UV-LED emitting a very narrow certain wavelength range make improvement of curability of the composition difficult. Therefore, use of the composition of the present disclosure, which has excellent curability even with UV-LED, is preferable.

<Application Field>

The application field of the composition of the present disclosure is not particularly limited. It can be applied to any field where active energy ray curable compositions are used. For example, the composition is selected to a particular application and used for a resin for processing, a paint, an adhesive, an insulant, a releasing agent, a coating material, a sealing material, various resists, and various optical materials.

Furthermore, the curable composition of the present disclosure can be used as an ink to form two-dimensional texts, images, and designed coating film on various substrates and in addition as a solid object forming material to form a three-dimensional object. This three dimensional object forming material may also be used as a binder for powder particles used in a powder layer laminating method of forming a three-dimensional object by repeating curing and layer-forming of powder layers, and as a three-dimensional object constituent material (a model material) and a supporting member used in an additive manufacturing method (a stereolithography method) as illustrated in FIG. 2, and FIG. 3. FIG. 2 is a diagram illustrating a method of additive manufacturing to sequentially form layers of the curable composition of the present disclosure one on top of the other by repeating discharging the curable composition to particular areas followed by curing upon irradiation of an active energy ray. FIG. 3 is a diagram illustrating a method of additive manufacturing to sequentially form cured layers 6 having respective predetermined forms one on top of the other on a movable stage 3 by irradiating a storing pool (storing part) 1 of the curable composition 5 of the present disclosure with the active energy ray 4.

An apparatus for fabricating a three-dimensional object by the composition of the present disclosure is not particularly limited and can be a known apparatus. For example, the apparatus includes a containing device, a supplying device, and a discharging device of the composition, and an active energy ray irradiator.

In addition, the present disclosure includes cured materials obtained by curing the curable composition and processed products obtained by processing structures having the cured materials on a substrate. The processed product is fabricated by, for example, heat-drawing and punching a cured material or structure having a sheet-like form or film-like form. Examples thereof are gauges or operation panels of vehicles, office machines, electric and electronic machines, and cameras.

The substrate is not particularly limited. It can suitably be selected to a particular application. Examples thereof include paper, thread, fiber, fabrics, leather, metal, plastic, glass, wood, ceramic, or composite materials thereof. Of these, plastic substrates are preferred in terms of processability.

<<Storage Container>>

The storage container of the present disclosure contains the curable composition and is suitable for the applications as described above. For example, if the curable composition of the present disclosure is used for ink, a container that stores the ink can be used as an ink cartridge or an ink bottle. Therefore, users can avoid direct contact with the ink during operations such as transfer or replacement of the ink, so that fingers and clothes are prevented from contamination. Furthermore, inclusion of foreign matters such as dust in the ink can be prevented. In addition, the container can be of any size, any form, and any material. For example, the container can be designed to a particular application. It is preferable to use a light blocking material to block the light or cover a container with a light blocking sheet, etc.

<<Image Forming Method and Image Forming Apparatus>>

The image forming method of the present disclosure may use active energy rays or heating. In order to cure the composition of the present disclosure with active energy rays, the image forming method includes an irradiating step including applying active energy rays, and the image forming apparatus of the present disclosure includes an irradiation unit configured to apply active energy rays, and a container configured to store therein the composition of the present disclosure. The container may store the container described above. Moreover, the image forming method and image forming apparatus may further include an ejection step and an ejection unit configured to eject the composition of the present disclosure, respectively. A method for ejecting the composition is not particularly limited. Examples thereof include continuous jet and on-demand ejection. Examples of the on-demand ejection include a piezo system, a thermal system, and an electrostatic system.

Printing units 23 a, 23 b, 23 c, and 23 d respectively having ink cartridges and discharging heads for yellow, magenta, cyan, and black curable inks discharge the inks onto a recording medium 22 fed from a supplying roller 21. Thereafter, light sources 24 a, 24 b, 24 c, and 24 d configured to cure the inks emit active energy rays to the inks, thereby curing the inks to form a color image. Thereafter, the recording medium 22 is conveyed to a processing unit 25 and a printed matter reeling roll 26. Each of the printing unit 23 a, 23 b, 23 c and 23 d may have a heating mechanism to liquidize the ink at the ink discharging portion. Moreover, in another embodiment of the present disclosure, a mechanism may optionally be included to cool down the recording medium to around room temperature in a contact or non-contact manner. In addition, the inkjet recording method may be either of serial methods or line methods. The serial methods include discharging an ink onto a recording medium by moving the head while the recording medium intermittently moves according to the width of a discharging head. The line methods include discharging an ink onto a recording medium from a discharging head held at a fixed position while the recording medium continuously moves.

The recording medium 22 is not particularly limited. Specific examples thereof include, but are not limited to, paper, film, metal, or composite materials thereof, each of which may be in the form of a sheet. The image forming apparatus may have a one-side printing configuration and/or a two-side printing configuration.

Optionally, multiple colors can be printed with no or weak active energy ray from the light sources 24 a, 24 b, and 24 c followed by irradiation of the active energy ray from the light source 24 c 1. As a result, energy and cost can be saved.

The recorded matter having images printed with the ink of the present disclosure includes articles having printed images or texts on a plain surface of conventional paper, resin film, etc., a rough surface, or a surface made of various materials such as metal or ceramic. In addition, by laminating layers of images in part or the entire of a recording medium, a partially stereoscopic image (formed of two dimensional part and three-dimensional part) and a three dimensional objects can be fabricated.

FIG. 2 is a schematic view illustrating another example of the image forming apparatus (apparatus to fabricate a 3D object) of the present disclosure. An image forming apparatus 39 illustrated in FIG. 2 sequentially forms and overlaps a substrate layer and forming layers to produce a solid molded article 35 with repeating the following step several times according to the number of layers to be laminated while lowering a stage 38 movable upwards and downwards. The above-mentioned step includes ejecting a first composition from the ejection head unit for forming 30, ejecting a composition from the ejection heads for supports 31 and 32, and applying active energy rays to cure and form a first formed layer using a head unit (movable in the directions indicated by the arrows A and B) in which the inkjet heads are aligned. Thereafter, the substrate laminate part 36 is removed according to the necessity. Although only a single ejection head unit 30 for forming is disposed in the image forming apparatus illustrated in FIG. 2, two or more ejection head units may be disposed.

EXAMPLES

The present disclosure will be described more specifically below by way of Examples and Comparative Examples. The present disclosure should not be construed as being limited to these Examples.

<Constitutional Components of Composition>

Abbreviations, compound names, manufacturers' names, and product names of raw materials used for preparing compositions are presented in Tables 1-1 and 1-3.

Raw materials that were not commercially available were synthesized according to the methods described in Synthesis Examples 1 to 9. The identification of the synthesized compound was performed by nuclear magnetic resonance spectroscopy (device for use: JNM-ECX500, available from JEOL Ltd.,), and the measurement of the purity was performed by gas chromatography (device for use: GCMS-QP2010 Plus, available from Shimadzu Corporation). The above-mentioned chemical analysis methods were performed by conventional methods.

TABLE 1-1 Product name and Abbreviation Name or structure of compound manufacturer's name Acrylamide compound having an ester structure and having a molecular weight of 150 to 250 (A1-1) A1-1-1

(See Synthesis Example 1) A1-1-2

(See Synthesis Example 2) A1-1-3

(See Synthesis Example 3) A1-1-4

(See Synthesis Example 4) A1-1-5

(See Synthesis Example 5) A1-1-6

(See Synthesis Example 6) A1-1-7

(See Synthesis Example 7) Acrylamide compound having an ester structure and having a molecular weight of less than 150 but greater than 250 (A1-2) A1-2-1

(See Synthesis Example 8) A1-2-2

(See Synthesis Example 9)

TABLE 1-2 Polymerizable compounds other than A1 (A2) A2-1

Gryceline triacrylate, M-3547 available from TOAGOSE CO. LTD. A2-2

TMPTA, Biscoat #295 available from OSAKA ORGANIC CHEMICAL INDUSTRY LTD. A2-3

TMPTMA, SR-350 available from OSAKA ORGANIC CHEMICAL INDUSTRY LTD. A2-4

A-TMMT, pentaerythritol tetraacrylate, available from Shin-Nakamura Chemical Co., Ltd. A2-5

DPIIA, dipentaerythritol hexaacrylate, available from Sartomer

TABLE 1-3 Product name and Abbreviation Name or structure of compound manufacturer's name Poly- B-1 1,3-di({α-chloro-9-oxo-9H-thioxanthen- Speedcure 7010 merization 4-yl)oxy]acetylpoly[oxy(1- available from Lmbson initiator methylethylene)]}oxy)- (B) 2,2-bis({α-[1-chloro-9-oxo-9H-thioxanthen-4- yl)oxy]acetylpoly[oxy(1-methylethylene)]}oxy methyl)propane B-2 mixture of 1,3-di({α-4- Speedcure 7040 (dimethylamino)benzoylpoly[oxy(1- available from Lmbson methylethylene)]}oxy)-2,2-bis({α-4- (dimethylamino)benzoylpoly[oxy(1- methylethylene)]}oxymethyl)propane and {α-4-(dimethylamino)benzoylpoly(oxyethylene)- poly[oxy(1-methylethylene)]- poly(oxyethylene)}4-(dimethylamino)benzoate B-3 oligomer of Esacure ONE 2-hydroxy-1-(4-isopropenylphenyl)-2-methyl available from IGM propan-1-one B-4 1-hydroxy-cyclohexyl-phenylketone Irgacure 184 available from BASF Japan B-5 2-(dimethylamino)-2-[(4-methylphenyl)methyl]- Irgacure 379 1-[4-(4-morpholinyl)phenyl]-1-butanone available from BASF Japan B-6 bis(2,4,6-trimethylbenzoyl)phenylphosphine Irgacure 819 oxide available from BASF Japan B-7 2-[4-(methylthio)benzoyl]-2-(4- Irgacure 907 morpholinyl)propane available from BASF Japan B-8 2,4,6-trimethylbenzoyl-diphenyl-phosphine Irgacure TPO oxide available from BASF Japan Other Poly- 4-methoxyphenol METHQUINONE Com- merization available from Seiko ponents Inhibitor Chemical Co., Ltd. Surfactant silicone-based surfactant BYK-UV3510 available from BYK Japan KK

Synthesis Example 1 Synthesis of N-acryloyl-N-methylglycine methyl ester (A1-1-1)

N-methylglycine methyl ester hydrochloride (reagent, available from Sigma-Aldrich Co., LLC.) in an amount of 0.30 mol, 0.45 mol of potassium carbonate (reagent, available from KANTO CHEMICAL CO., INC.), and 400 mL of water were stirred and mixed at a temperature of from 0° C. through 10° C. With maintaining the temperature, 0.33 mol of acrylic acid chloride (reagent, available from Wako Pure Chemical Industries, Ltd.) was slowly dripped. After completing the dripping, extraction was performed 3 times with 400 mL of ethyl acetate (reagent, available from KANTO CHEMICAL CO., INC.), and the resultant ethyl acetate layers were combined and washed with 400 mL of water once. The ethyl acetate was removed under the reduced pressure at 40° C., to thereby obtain 0.20 mol of targeted N-acryloyl-N-methylglycine methyl ester (A1-1-1) as a substantially colorless transparent liquid. The purity thereof was 98.3% by mass.

Note that, a molecular weight of N-acryloyl-N-methylglycine methyl ester (A1-1-1) was 157.2. N-acryloyl-N-methylglycine methyl ester (A1-1-1) is a known compound (CAS registry number: 72065-23-7).

Synthesis Example 2 Synthesis of N-acryloyl-N-isopropylglycine isopropyl ester (A1-1-2)

Targeted N-acryloyl-N-isopropylglycine isopropyl ester (A1-1-2) (0.22 mol) was obtained as a substantially colorless transparent liquid in the same manner as in Synthesis Example 1, except that N-methylglycine methyl ester hydrochloride was replaced with N-isopropylglycine isopropyl ester hydrochloride (reagent, available from Tokyo Chemical Industry Co., Ltd.). The purity thereof was 98.5% by mass.

Note that, a molecular weight of N-acryloyl-N-isopropylglycine isopropyl ester (A1-1-2) was 213.3.

Synthesis Example 3 Synthesis of N-acryloyl-N-isopropylglycine methyl ester (A1-1-3)

Targeted N-acryloyl-N-isopropylglycine methyl ester (A1-1-3) (0.22 mol) was obtained as a substantially colorless transparent liquid in the same manner as in Synthesis Example 1, except that N-methylglycine methyl ester hydrochloride was replaced with N-isopropylglycine methyl ester hydrochloride (reagent, available from Tokyo Chemical Industry Co., Ltd.). The purity thereof was 98.5% by mass.

Note that, a molecular weight of N-acryloyl-N-isopropylglycine methyl ester (A1-1-3) was 185.2.

Synthesis Example 4 Synthesis of N-acryloyl-N-methylalanine methyl ester (A1-1-4)

Targeted N-acryloyl-N-methylalanine methyl ester (A1-1-4) (0.22 mol) was obtained as a substantially colorless transparent liquid in the same manner as in Synthesis Example 1, except that N-methylglycine methyl ester hydrochloride was replaced with N-methylalanine methyl ester hydrochloride (reagent, available from Tokyo Chemical Industry Co., Ltd.). The purities thereof was 98.5% by mass.

Note that, a molecular weight of N-acryloyl-N-methylalanine methyl ester (A1-1-4) was 171.2.

Synthesis Example 5 Synthesis of N-acryloyl-N-methylglycine isopropyl ester (A1-1-5)

Targeted N-acryloyl-N-methylglycine isopropyl ester (A1-1-5) (0.22 mol) was obtained as a substantially colorless transparent liquid in the same manner as in Synthesis Example 1, except that N-methylglycine methyl ester hydrochloride was replaced with N-methylglycine isopropyl ester hydrochloride (reagent, available from Tokyo Chemical Industry Co., Ltd.). The purity thereof was 98.5% by mass.

Note that, a molecular weight of N-acryloyl-N-methylglycine isopropyl ester (A1-1-5) was 185.2.

Synthesis Example 6 Synthesis of N-acryloyl-N-methylalanine isopropyl ester (A1-1-6)

Targeted N-acryloyl-N-methylalanine isopropyl ester (A1-1-6) (0.22 mol) was obtained as a substantially colorless transparent liquid in the same manner as in Synthesis Example 1, except that N-methylglycine methyl ester hydrochloride was replaced with N-methylalanine isopropyl ester hydrochloride (reagent, available from Tokyo Chemical Industry Co., Ltd.). The purity thereof was 98.5% by mass.

Note that, a molecular weight of N-acryloyl-N-methylalanine isopropyl ester (A1-1-6) was 199.3.

Synthesis Example 7 Synthesis of ethyl N-acryloylpiperidine-4-carboxylate (A1-1-7)

Targeted ethyl N-acryloylpiperidine-4-carboxylate (A1-1-7) (0.27 mol) was obtained as a substantially colorless transparent liquid in the same manner as in Synthesis Example 1, except that N-methylglycine methyl ester hydrochloride was replaced with ethyl piperidine-4-carboxylate hydrochloride (reagent, available from Tokyo Chemical Industry Co., Ltd.). The purity thereof was 99.2% by mass.

Note that, a molecular weight of ethyl N-acryloylpiperidine-4-carboxylate (A1-1-7) was 211.3. Ethyl N-acryloylpiperkline-4-carboxylate (A1-1-7) is a known compound (CAS registry number: 845907-79-1).

Synthesis Example 8 Synthesis of N-acryloylalanine methyl ester (A1-2-1)

Targeted N-acryloylalanine methyl ester (A1-2-1) (0.21 mol) was obtained as a substantially colorless transparent liquid in the same manner as in Synthesis Example 1, except that N-glycine methyl ester hydrochloride was replaced with alanine methyl ester hydrochloride (reagent, available from Tokyo Chemical Industry Co., Ltd.). The purity was 99.5% by mass.

Note that, a molecular weight of N-acryloylalanine methyl ester (A1-2-1) was 143.1.

Synthesis Example 9 Synthesis of N-acryloyl N-pentylalanine pentyl ester (A1-2-2)

Targeted N-acryloyl N-pentylalanine pentyl ester (A1-2-2) (0.20 mol) was obtained as a substantially colorless transparent liquid in the same manner as in Synthesis Example 1, except that N-glycine methyl ester hydrochloride was replaced with N-pentylalanine pentyl ester hydrochloride (reagent, available from Tokyo Chemical Industry Co., Ltd.). The purity thereof was 99.5% by mass.

Note that, a molecular weight of N-acryloyl N-pentylalanine pentyl ester (A1-2-2) was 269.4.

Example 1 <Production of Composition>

A composition of Example 1 was produced by adding 83.8% by mass of A1-1-1, 10.0% by mass of A2-1, 3.0% by mass of B-1, 3.0% by mass of B-2, 0.1% by mass of a polymerization inhibitor, and 0.1% by mass of a surfactant in this order, stirring the resultant mixture for 2 hours, and visually confirming that there was no undissolved component remained, followed by removing coarse particles through filtration with a membrane filter.

Examples 2 to 33 and Comparative Examples 1 to 14

Compositions of Examples 2 to 33 and Comparative Examples 1 to 14 were each produced in the same manner as in Example 1, except that the composition and the amounts (% by mass) were changed as presented in Tables 2 to 7 below.

TABLE 2 Example 1 2 3 4 5 6 7 8 9 10 Acrylamide A1-1-1 83.8 78.0 78.0 78.0 compound A1-1-2 83.8 having ester A1-1-3 83.8 structure A1-1-4 83.8 and A1-1-5 83.8 molecular A1-1-6 83.8 weight of A1-1-7 83.8 150 to 250 (A1-1) Acrylamide A1-2-1 compound A1-2-2 having molecular weight of less than 150 or greater than 250 (A1-2) Polymerizable A2-1 10.0 10.0 10.0 10.0 10.0 10.0 10.0 15.8 compound A2-2 15.8 other than A2-3 15.8 (A1-1) and A2-4 (A1-2) A2-5 Polymerization B-1 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0 initiator B-2 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0 B-3 B-4 B-5 B-6 B-7 B-8 Other Polymerization 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 components inhibitor Surfactant 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 Total (mass %) 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0

TABLE 3 Example 11 12 13 14 15 16 17 18 19 20 Acrylamide A1-1-1 78.0 78.0 84.8 84.8 84.8 84.8 84.8 79.0 79.0 79.0 compound A1-1-2 haying ester A1-1-3 structure and A1-1-4 molecular A1-1-5 weight of 150 A1-1-6 to 250 (A1-1) A1-1-7 Acrylamide A1-2-1 compound A1-2-2 having molecular weight of less than 150 or greater than 250 (A1-2) Polymerizable A2-1 10.0 15.8 compound A2-2 10.0 15.8 other than A2-3 10.0 15.8 (A1-1) and A2-4 15.8 10.0 (A1-2) A2-5 15.8 10.0 Polymerization B-1 3.0 3.0 initiator B-2 3.0 3.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 B-3 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0 B-4 B-5 B-6 B-7 B-8 Other Polymerization 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 components inhibitor Surfactant 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 Total (mass %) 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0

TABLE 4 Example 21 22 23 24 25 26 27 28 29 30 Acrylamide A1-1-1 84.8 74.8 84.8 74.8 84.8 84.8 90.8 82.8 82.8 82.8 compound A1-1-2 having ester A1-1-3 structure A1-1-4 and A1-1-5 molecular A1-1-6 weight of A1-1-7 150 to 250 (A1-1) Acrylamide A1-2-1 compound A1-2-2 having molecular weight of less than 150 or greater than 250 (A1-2) Polymerizable A2-1 10.0 20.0 compound A2-2 10.0 20.0 9.0 other than A2-3 (A1-1) and A2-4 (A1-2) A2-5 10.0 10.0 10.0 9.0 9.0 Polymerization B-1 4.0 4.0 initiator B-2 4.0 4.0 B-3 5.0 9.0 4.0 B-4 5.0 4.0 B-5 5.0 B-6 5.0 B-7 5.0 B-8 5.0 Other Polymerization 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 components inhibitor Surfactant 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 Total (mass %) 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0

TABLE 5 Example 31 32 33 Acrylamide A1-1-1 90.8 61.8 71.8 compound A1-1-2 having ester A1-1-3 structure and A1-1-4 molecular A1-1-5 weight of 150 to A1-1-6 250 (A1-1) A1-1-7 Acrylamide A1-2-1 compound having A1-2-2 molecular weight of less than 150 or greater than 250 (A1-2) Polymerizable A2-1 1.0 30.0 10.0 compound other A2-2 10.0 than (A1-1) and A2-3 (A1-2) A2-4 A2-5 Polymerization B-1 4.0 4.0 initiator B-2 4.0 4.0 B-3 4.0 B-4 4.0 B-5 B-6 B-7 B-8 Other Polymerization 0.1 0.1 0.1 components inhibitor Surfactant 0.1 0.1 0.1 Total (mass %) 100.0 100.0 100.0

TABLE 6 Comparative Example 1 2 3 4 5 6 7 8 9 10 Acrylamide A1-1-1 compound A1-1-2 having ester A1-1-3 structure A1-1-4 and A1-1-5 molecular A1-1-6 weight of A1-1-7 150 to 250 (A1-1) Acrylamide A1-2-1 compound A1-2-2 having molecular weight of less than 150 or greater than 250 (A1-2) Polymerizable A2-1 94.8 93.8 compound A2-2 94.8 94.8 other than A2-3 94.8 94.8 (A1-1) and A2-4 94.8 94.8 (A1-2) A2-5 94.8 94.8 Polymerization B-1 5.0 3.0 3.0 initiator B-2 5.0 2.0 3.0 B-3 5.0 B-4 5.0 B-5 5.0 B-6 5.0 B-7 5.0 B-8 5.0 Other Polymerization 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 components inhibitor Surfactant 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 Total (mass %) 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0

TABLE 7 Comparative Example 11 12 13 14 Acrylamide A1-1-1 compound A1-1-2 93.4 having ester A1-1-3 62.8 structure and A1-1-4 molecular A1-1-5 weight of 150 to A1-1-6 250 (A1-1) A1-1-7 Acrylamide A1-2-1 83.8 compound having A1-2-2 83.8 molecular weight of less than 150 or greater than 250 (A1-2) Polymerizable A2-1 10.0 10.0 0.4 31.0 compound other A2-2 than (A1-1) and A2-3 (A1-2) A2-4 A2-5 Polymerization B-1 3.0 3.0 3.0 3.0 initiator B-2 3.0 3.0 3.0 3.0 B-3 B-4 B-5 B-6 B-7 B-8 Other Polymerization 0.1 0.1 0.1 0.1 components inhibitor Surfactant 0.1 0.1 0.1 0.1 Total (mass %) 100.0 100.0 100.0 100.0

Next, the viscosity of each of the obtained compositions was measured at 25° C. in the following manner. The results are presented in Tables 8 to 13.

<Measurement of Viscosity>

Viscosity of each composition was measured by means of a cone plate rotatory viscometer VISCOMETER TVE-22L available from TOKI SANGYO CO., LTD. using a cone rotor (1°34′×R24) at 50 rpm with setting a temperature of constant temperature circulating water to 25° C. For adjusting the temperature of the circulating water, VISCOMATE VM-150III was used. Note that, practical use of the composition can be realized in view of ejection stability, hardness, and curing shrinkage when the viscosity of the composition is 60 mPa·s or less at 25° C.

<Formation of Printed Image by Inkjet>

A plastic storage container was charged with each composition, and the storage container was mounted in an image forming apparatus including an inkjet head (MH5440, available from Ricoh Company Limited) serving as an ejection unit, a UV-LED (LED ZERO, available from INTEGRATION TECHNOLOGY LTD., wavelength: 395 nm, illuminance on illumination surface: 1.0 W/cm²) serving as an active energy-ray irradiation unit, a controller configured to control ejection, and a supply channel from the storage container and the inkjet head.

The temperature of the inkjet head was appropriately adjusted to adjust the viscosity of the composition in the range of from 10 mPa·s through 12 mPa·s. The composition was ejected onto a readily available film material, that was a commercially available PET film (COSMOSHINE A4100 available from TOYOBO CO., LTD., thickness: 188 μm) by inkjet to give a film thickness of 10 μm, followed by performing UV ray irradiation with the UV-LED, to thereby produce a cured product.

[Evaluation of Hardness]

The state of the coated film on which stickiness was not felt with fingers when touched with the fingers was determined as cured. The integrated irradiation light dose required for curing was determined. The results are presented in Tables 8 to 13. The case where the integrated irradiation light dose required for curing was 1.0 J/cm² or less was determined as practically usable.

<Hardness>

Pencil hardness of the obtained cured product was measured according to JIS K5600-5-4 scratch hardness (pencil method), and the “hardness” was evaluated based on the following evaluation criteria. The results are presented in Tables 8 to 13. Note that, the case where the hardness was HB or harder was determined as practically usable.

—Device and Equipment—

-   Device: scratch pencil hardness TQC WW tester (for load of 750 g)     available from COTEC -   Pencil: wooden pencil set for technical drawing (available from     Mitsubishi Pencil Co., Ltd.) of the following hardness: -   6B, 5B, 4B, 3B, 2B, B, HB, F, H, 2H, 3H, 4H, 5H, 6H -   Pencil sharpener: special sharpener designed to scrape only the     wooden part with remaining a cylindrical core of the pencil

When the ink having low curability was cured with the above-mentioned light dose, the ink was not sufficiently cured and therefore hardness of the cured product was also low.

TABLE 8 Example 1 2 3 4 5 6 7 8 9 10 Integrated  0.5  0.8  0.5  0.8  0.5  0.6  0.6  0.5  0.6  0.5 irradiation light dose required for curing (J/cm²) Pencil hardness H 2H 2H H H H H H H H Viscosity (mPa · s) 12.5 13.1 11.6 14.2 11.8 12.9 13.1 19.4 25.1 20.3

TABLE 9 Example 11 12 13 14 15 16 17 18 19 20 Integrated  0.5  0.8  0.5  0.8  0.5  0.6  0.6  0.5  0.6  0.5 irradiation light dose required for curing (J/cm²) Pencil hardness F F HB F F H H H F F Viscosity (mPa · s) 23.4 26.4 14.2 15.3 17.0 16.4 16.1 22.2 22.9 20.8

TABLE 10 Example 21 22 23 24 25 26 27 28 29 30 Integrated  0.5  0.8  0.5  0.8  0.5  0.6  0.6  0.5  0.6  0.5 irradiation light dose required for curing (J/cm²) Pencil hardness HB HB F F H H H F F F Viscosity (mPa · s) 10.2 16.6 19.8 23.5 12.2 11.1 15.8 16.1 17.2 16.5

TABLE 11 Example 31 32 33 Integrated irradiation light dose 1.0 0.4 0.5 required for curing (J/cm²) Pencil hardness HB 2H F Viscosity (mPa · S) 11.0 59.0 45.0

TABLE 12 Comparative Example 1 2 3 4 5 6 7 8 9 10 Integrated *1 *1 *1 *1 *1 0.5 0.6 0.7 0.6 *1 irradiation light dose required for curing (J/cm²) Pencil hardness — 6B 6B 6B 6B HB B 2B HB 6B Viscosity 65.0 90.0 121.0 790.0 4400.0 101.0 136.0 870.0 5000.0 74.0 (mPa · s)

-   In Table 12, “*1” means that the composition was not cured with the     integrated irradiation light dose of 100 J/cm². -   In Table 12, the pencil hardness “−” of Comparative Example 1 means     that it was impossible to measure.

TABLE 13 Comparative Example 11 12 13 14 Integrated 0.6 0.7 1.0 0.8 irradiation light dose required for curing (J/cm²) Pencil hardness 2B 2B B F Viscosity 289.0 305.0 10.0 96.0 (mPa · S)

For example, embodiments of the present disclosure are as follows.

<1> A composition including;

-   an acrylamide compound (A1) having a molecular weight of 150 or     greater but 250 or less; and -   a trifunctional or higher polymerizable compound (A2), -   wherein an amount of the trifunctional or higher polymerizable     compound (A2) is 1% by mass or greater but 30% by mass or less     relative to a total amount of the composition.     <2> The composition according to <1>, -   wherein the acrylamide compound (A1) is represented by General     Formula (1) below, or General Formula (2) below, or both,

CH₀═CH—CO—N(R¹)—R²—CO—O—R³   General Formula (1)

where, in General Formula (1), R¹ is a hydrogen atom or a straight chain or branched alkyl group having from 1 through 4 carbon atoms, R² is a straight chain or branched alkylene group having from 1 through 4 carbon atoms, and R³ is a straight chain or branched alkyl group having from 1 through 4 carbon atoms, with the proviso that a total number of carbon atoms of R¹, R², and R³ is from 2 through 6,

where, in General Formula (2), a ring X is a cyclic structure that includes a nitrogen atom and has from 2 through 5 carbon atoms, R⁴ is a single bond or a straight chain or branched alkylene group having from 1 through 3 carbon atoms, and R⁵ is a straight chain or branched alkyl group having from 1 through 3 carbon atoms, with the proviso that a total number of carbon atoms of the ring X, R⁴, and R⁵ is from 3 through 6. <3> The composition according to <2>,

-   wherein the acrylamide compound (A1) is represented by General     Formula (1) and R³ is an alkyl group having from 1 through 2 carbon     atoms.     <4> The composition according to any one of <1> to <3>, -   wherein the amount of the acrylamide compound (A1) is 20.0% by mass     or greater but 98.0% by mass or less relative to a total amount of     the composition.     <5> The composition according to any one of <1> to <4>, -   wherein the trifunctional or higher polymerizable compound (A2) is a     trifunctional or higher but hexafunctional or lower polymerizable     compound.     <6> The composition according to <5>, -   wherein the trifunctional or higher polymerizable compound (A2) is a     trifunctional polymerizable compound.     <7> The composition according to any one of <1> to <6>, -   wherein the trifunctional or higher polymerizable compound (A2) is     at least one selected from the group consisting of glycerin     tri(meth)acrylate, pentaerythritol tri(meth)acrylate,     trimethylolpropane tri(meth)acrylate, and trimethylolpropane     tri(meth)acrylate.     <8> The composition according to any one of <1> to <7>, -   wherein an amount of the trifunctional or higher polymerizable     compound (A2) is 5% by mass or greater but 20% by mass or less     relative to the total amount of the composition.     <9> The composition according to any one of <1> to <8>, -   wherein the composition has viscosity of 60 mPa·s or less at 25° C.     <10> The composition according to <9>, -   wherein the composition has viscosity of 5 mPa·s or greater but 30     mPa·s or less at 25° C.     <11> The composition according to any one of <1> to <10>, further     including a polymerization initiator.     <12> The composition according to any one of <1> to <11>, -   wherein the composition is free from an organic solvent.     <13> The composition according to any one of <1> to <12>, -   wherein the composition is an active energy ray-curable composition.     <14> The composition according to any one of <1> to <13>, -   wherein the composition is an inkjet composition.     <15> A storage container including: -   a container; and -   the composition according to any one of <1> to <14>, where the     composition is stored in the container.     <16> A two-dimensional or three-dimensional image forming apparatus,     the apparatus including: -   a container, in which the composition according to any one of <1> to     <14> is stored; -   an application unit configured to apply the composition; and -   a curing unit configured to cure the composition.     <17> The apparatus according to <16>, -   wherein the curing unit is a UV-LED configured to emit ultraviolet     rays having a peak at a wavelength of 365 nm or longer but 405 nm or     shorter.     <18> A two-dimensional or three-dimensional image forming method,     the method including: -   applying the composition according to any one of <1> to <14>; and     curing the composition.     <19> The method according to <18>, -   wherein the curing includes applying ultraviolet rays having a peak     at a wavelength of 365 nm or longer but 405 nm or shorter using a     UV-LED. -   <20> A cured product obtained with the composition according to any     one of <1> to <14>.     <21> A formed article obtainable by stretching the cured product     according to <20>.     <22> A decorated article obtainable by applying on a base a surface     decoration formed of the cured product according to <20>.

The composition according to any one of <1> to <14>, the storage container according to <15>, the two-dimensional or three-dimensional image forming apparatus according to <16> or <17>, the two-dimensional or three-dimensional image forming method according to <18> or <19>, the cured product according to <20>, the formed article according to <21>, and the decorated article according to <22> can solve the above-described various problems existing in the art and can achieve the object of the present disclosure. 

What is claimed is:
 1. A composition comprising: an acrylamide compound (A1) having a molecular weight of 150 or greater but 250 or less; and a trifunctional or higher polymerizable compound (A2), wherein an amount of the trifunctional or higher polymerizable compound (A2) is 1% by mass or greater but 30% by mass or less relative to a total amount of the composition.
 2. The composition according to claim 1, wherein the acrylamide compound (A1) is represented by General Formula (1) below, or General Formula (2) below, or both, CH₂═CH—CO—N(R¹)—R²—CO—O—R³   General Formula (1) where, in General Formula (1), R¹ is a hydrogen atom or a straight chain or branched alkyl group having from 1 through 4 carbon atoms, R² is a straight chain or branched alkylene group having from 1 through 4 carbon atoms, and R³ is a straight chain or branched alkyl group having from 1 through 4 carbon atoms, with the proviso that a total number of carbon atoms of R¹, R², and R³ is from 2 through 6,

where, in General Formula (2), a ring X is a cyclic structure that includes a nitrogen atom and has from 2 through 5 carbon atoms, R⁴ is a single bond or a straight chain or branched alkylene group having from 1 through 3 carbon atoms, and R⁵ is a straight chain or branched alkyl group having from 1 through 3 carbon atoms, with the proviso that a total number of carbon atoms of the ring X, R⁴, and R⁵ is from 3 through
 6. 3. The composition according to claim 2, wherein the acrylamide compound (A1) is represented by General Formula (1) and R³ is an alkyl group having from 1 through 2 carbon atoms.
 4. The composition according to claim 1, wherein the trifunctional or higher polymerizable compound (A2) is a trifunctional or higher but hexafunctional or lower polymerizable compound.
 5. The composition according to claim 4, wherein the trifunctional or higher polymerizable compound (A2) is a trifunctional polymerizable compound.
 6. The composition according to claim 1, wherein the trifunctional or higher polymerizable compound (A2) is at least one selected from the group consisting of glycerin tri(meth)acrylate, pentaerythritol tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, and trimethylolpropane tri(meth)acrylate.
 7. The composition according to claim 1, wherein an amount of the trifunctional or higher polymerizable compound (A2) is 5% by mass or greater but 20% by mass or less relative to the total amount of the composition.
 8. The composition according to claim 1, wherein the composition has viscosity of 60 mPa·s or less at 25° C.
 9. The composition according to claim 8, wherein the composition has viscosity of 5 mPa·s or greater but 30 mPa·s or less at 25° C.
 10. The composition according to claim 1, wherein the composition is free from an organic solvent.
 11. The composition according to claim 1, wherein the composition is an active energy ray-curable composition.
 12. The composition according to claim 1, wherein the composition is an inkjet composition.
 13. A storage container comprising: a container; and the composition according to claim 1, where the composition is stored in the container.
 14. A two-dimensional or three-dimensional image forming apparatus, the apparatus comprising: a container, in which a composition is stored; an application unit configured to apply the composition; and a curing unit configured to cure the composition, wherein the composition includes: an acrylamide compound (A1) having a molecular weight of 150 or greater but 250 or less; and a trifunctional or higher polymerizable compound (A2), wherein an amount of the trifunctional or higher polymerizable compound (A2) is 1% by mass or greater but 30% by mass or less relative to a total amount of the composition.
 15. The image forming apparatus according to claim 14, wherein the curing unit is a UV-LED configured to emit ultraviolet rays having a peak at a wavelength of 365 nm or longer but 405 nm or shorter.
 16. A two-dimensional or three-dimensional image forming method, the method comprising: applying a composition; and curing the composition, wherein the composition includes: an acrylamide compound (A1) having a molecular weight of 150 or greater but 250 or less; and a trifunctional or higher polymerizable compound (A2), wherein an amount of the trifunctional or higher polymerizable compound (A2) is 1% by mass or greater but 30% by mass or less relative to a total amount of the composition.
 17. The method according to claim 16, wherein the curing includes applying ultraviolet rays having a peak at a wavelength of 365 nm or longer but 405 nm or shorter using a UV-LED.
 18. A cured product obtained with the composition according to claim
 1. 19. A formed article obtainable by stretching the cured product according to claim
 18. 20. A decorated article obtainable by applying on a base a surface decoration formed of the cured product according to claim
 18. 